The present invention generally concerns improved processes or techniques for ensuring the integrity of meters during power outages, and more particularly concerns improved memory integrity of electricity meters such that the memory is always in a state that previous data may be retrieved. The subject invention concerns both apparatus and methodology in such areas, including the use of practical computer software applications involving an algorithm approach to producing a useful, concrete and tangible result, i.e., namely, a stored data value for consumed electricity (or other commodity) to be charged to a customer's account.
The general object of metrology (i.e., the science of measurement) is to monitor a physical phenomenon to permit a record of the monitored event(s). If the potential to record the measured or monitored data is lost, then the entire basic purpose of the metering device and/or effort fails.
Such basic function and purpose of metering devices can be applied to a number of contexts. One broad area of measurement relates, for example, to utility meters. These may include the monitoring of consumption of a variety of forms of energy or other commodities, such as electricity, water, gas, and oil, to name a few.
Historically, a mechanical form of register was used for utility meters. Such an approach provided a relatively dependable field device with certain inherent functional advantages. For example, if the flow of the consumable commodity being measured was interrupted, the mechanical form of gauge simply stopped in its place, automatically reflecting the previous accumulation without other arrangements being required, and without any loss of such accumulated data. After resumption of the flow of the commodity, the mechanical register could then simply begin to add additional flow values to the previous accumulation, so that accurate data was reflected at all times regardless of intermittent commodity flow interruptions.
Also, in many instances, the gauge or register required no separate power supply since it was operated directly by the commodity flow. In the case of electricity meters, the mechanical register could be electrically powered. Hence, when power was lost, the measurement function was temporarily moot so no measurement functionality was lost even though the gauge itself would be temporarily without power.
As the technology of metering devices progressed, mechanical registers began to be replaced with more electrical-based devices and electronic forms of registers. Generally speaking, all such devices require some form of electrical power for their operation and data storage function. Such fact created the potential for catastrophic loss of accumulated data (i.e., the failure of the entire purpose of the measuring device if data representing accumulated commodity usage were lost).
For example, in the case of an electricity meter, electric power is already flowing to (and through) the metering or measuring device. Such fact makes for a convenient supply of electricity, without having to attempt to rely on battery operation or some other source of electrical power. However, such an arrangement, while advantageous in certain aspects, is inherently susceptible to the loss of electrical power to the measuring device (including its register) at the same time there is any power loss to the customer's location (for example, house or business).
Intermittent power outages (or other conditions, such as brown outs) can occur in even the best maintained systems. For example, an electrical power system can become damaged due to storm debris (e.g., falling limbs) or high winds, or from an accident (for example, vehicles such as trucks or cars knocking down utility poles and power lines). Under certain load shedding conditions, it may even become necessary for power to a given location to be deliberately interrupted.
Regardless of such causes (or possibly other sources) of power outages, the inherent problem is that an electrical measuring device with an electrically powered register may lose its accumulated data in the event of a routine power outage. Prior attempts have been made to address such technical problem.
In one instance, a technique or storage algorithm was used to store electricity meter quantities to a non-volatile memory whenever a power outage occurred. In such prior attempt, the technique involved a relatively early detection of the power outage and consideration of the power supply hold up times to complete the storage of the electricity meter quantities to the non-volatile memory. Such so-called "hold up time" refers to the amount of time a supply will maintain acceptable output power to the circuit after line voltage is removed. Hence, such technique involved the use of relatively complicated and costly power fail detection circuits and power supply hold up components. In addition, most non-volatile memory devices are limited by the maximum number of times an area of memory could be written to over the life of such a device.
Other arrangements and aspects of electronic-based electricity meters are known. See, for example, disclosures set forth in U.S. Pat. Nos. 4,783,623; 5,469,049 and 4,509,128. The disclosures of all such patents are hereby incorporated herein by reference.